The 19-times capped stand-off sustained a head injury in Glasgow Warriors’ Guinness Pro12 play-off defeat by Connacht in Galway on Saturday. Glasgow announced on Tuesday he would not require surgery.
It expected a replacement for the tour will be named shortly.
The Scotland squad will gather at BT Murrayfield on Monday for a short camp before they leave for Tokyo the following Saturday, 11 June.
Scotland will play two Tests against Japan on consecutive Saturdays at J1 League football stadia; the first at the Toyota Stadium in Toyota City (18 June), the second at the Ajinomoto Stadium in Tokyo (25 June), homes of Nagoya Grampus and FC Tokyo respectively.
Glasgow coach Gregor Townsend called it “a very serious injury” when Russell collided with team-mate Zander Fagerson, who subsequently also failed a head injury assesssment, in the first minute of Saturday’s defeat at Connacht.
Russell required oxygen and, after initially being treated at the University Hospital in Galway, was transferred to Beaumont Hospital in Dublin and is now expected to be discharged later this week.
A Glasgow Warriors statement said: “His condition has improved significantly over the last couple of days and it’s been confirmed that he does not require surgery.
“His return to training date will be determined when he is back in Glasgow.
“Glasgow Warriors would like to thank the Connacht medical team, players and staff for their support. The club would also like to thank the University Hospital in Galway and Beaumont Hospital in Dublin for all their help.
“Finn and his family really appreciate all the messages of support, with which they have been inundated.
“Other players are still being assessed by the Glasgow Warriors medical team following Saturday’s match against Connacht.”